1. Field of the Invention
This invention relates to Magnetic Resonance Imaging, and more specifically, a coil for producing a magnetic field gradient for Magnetic Resonance Imaging which allows access to the patient being imaged.
2. Description of Related Art
In Magnetic Resonance (MR) imaging, a patient desired to be imaged is positioned within a main magnet, which produces a static magnetic field, and near by radiofrequency coils and magnetic gradient coils. The gradient coils are energized to produce magnetic fields through interaction with a static magnetic field produced by a main magnet. Radiofrequency (RF) excitation pulses are applied to the RF coils to radiate RF energy through the patient, nutating resonating nuclei "nuclear spins". These nutated nuclear spins produce a spatial position encoded MR response signal when proper magnetic field gradients are applied to them.
Typically, to produce a homogeneous magnetic field over the patient, the main magnet has a cylindrical shape which surrounds the patient, preserving radial symmetry. The gradient coils are also cylindrically shaped and fit inside the main magnetic and also surround the patient. U.S. Pat. No. 4,646,024, "Transverse Gradient Field Coils for Nuclear Magnetic Resonance Imaging" issued Feb. 24, 1987 to Schenck, J. F., Hussain, M. A., Edelstein, W. A., and assigned to the instant assignee, describes the design of whole body gradient coils. Access to the patient is, therefore, severely limited due to the geometry of the main magnet in gradient coils.
Since MR imaging provides high resolution images of various types of soft tissue, and may more readily differentiate tissue types, it would be beneficial to a surgeon to have a "snapshot" or "movie" of internal structures of the patient during surgery. This may assist the surgeon in his procedures.
In addition to limited access, patients typically develop a claustrophobic reaction during imaging.
Therefore, an open MR imaging system employing open gradient coils is needed which would allow a maximum access to the patient allowing medical procedures to be performed on a patient while still providing high resolution images of the patient. In addition, an open MR imaging system would reduce the claustrophobic reaction of the patients.